去除水中硝酸盐的高效复合光催化剂及催化反应路径研究

硝酸盐污染在全球范围普遍存在，可引起水华等生态环境问题，严重影响人类健康和经济社会可持续发展。目前仍缺少高效去除水中硝酸盐的低成本方法。本项目提出一种基于固态Z-Scheme电荷转移机制的钒酸铋/石墨烯/铁酸锌@银-M(M为镍、铂或钯)复合光催化剂，在太阳光照射下，将水中的硝酸盐还原为氮气，从而降低水中氮浓度。通过水热、原位光还原等方法合成该复合结构，其中铁酸锌产生的光生电子直接还原硝酸盐；银-M纳米颗粒作为助催化剂，提高催化活性和选择性；钒酸铋氧化水，为硝酸盐还原提供质子。该催化剂吸光范围宽，能在中性水中工作，不需额外添加剂，且产生氧气，增加水中溶解氧。此外，结合原位光谱（拉曼和红外）表征技术和密度泛函理论计算，揭示硝酸盐光催化还原的反应路径和机理。该项目将为发展基于光催化的高效廉价除氮技术提供重要科学依据和材料基础，对保护饮用水安全、生态环境和人类健康具有重要经济价值和社会意义。

Nitrate pollution is ubiquitous all over the world, which can cause water blooms and other ecological environment problems, seriously endangering human health and sustainable development. At present, there is still a lack of efficient and low-cost methods for nitrate removal from water. In this project, a bismuth vanadate/graphene/zinc ferrite@silver-M (M is nickel, platinum or palladium) composite photocatalyst based on solid Z-Scheme charge transfer mechanism is proposed. Nitrate in water is reduced to nitrogen only under sunlight, thus reducing nitrogen concentration in water. The composite structure is synthesized by hydrothermal and in-situ photoreduction methods, of which nitrate is directly reduced by photogenerated electrons from zinc ferrite; Ag-M hybrid nanoparticles are used as co-catalysts to improve catalytic activity and selectivity; bismuth vanadate provides protons for nitrate reduction by oxidizing. The catalyst has advantages of wide absorption range, working in neutral water without additional additives, and generate of oxygen to increase dissolved oxygen in water. Furthermore, by combining in-situ spectroscopy (Raman and infrared absorption) characterization technology and density functional theory calculation, basic scientific issues such as the reaction path and mechanism of photocatalytic nitrate reduction will be revealed. The project will provide important scientific and material basis for the development of photocatalytic technology for removing nitrate pollution, and has important economic value and social significance in field of protection of water resources, ecological environment and human health.